1. Field of the Invention
The present invention is directed to an improved primary air distribution manifold for use on air seeder, wherein the manifold is provided with a selector valve for directing product to different ranks of venturis.
2. Description of the Prior Art
Air seeders and other seeding devices are commonly towed by tractors to apply seed or fertilizer, or both simultaneously, to a field. As an example, an air seeder may be towed in combination with a tilling implement, one behind the other, to place seed and fertilizer under the surface of the soil. An air seeder has as its central component a wheeled seed cart which comprises one or more frame-mounted product tanks for holding product, generally seed or fertilizer or both. Air seeders also generally comprise a metering system for dispensing product from the tanks and a pneumatic distribution system for delivering the product from tank to soil.
It is known to provide an air seeder with volumetric meters which measure a fixed volume of seed per unit of linear distance. These volumetric meters typically comprise either augers or fluted cylinders (meter rollers) which rotate through a product reservoir to measure granular product. The meters rotate to feed product into a pneumatic distribution system. The pneumatic distribution system of an air seeder generally utilizes a blower to provide at least one airstream which flows through the pneumatic distribution system to seed boots where product is deposited in the soil. Metered product is introduced into the air stream at a primary air distribution manifold located below the product meter. Product is carried by the air stream through distribution lines to a series of secondary distribution manifolds ("headers"), which in turn distribute product through individual lines to seed boots mounted behind ground openers on the tilling implement.
Operators of conventional seeding equipment have problems configuring distribution manifolds for accepting metered product from multiple tanks entering into the pneumatic distribution systems. When an operator wants to switch tank applications or the setup of the tilling implement, the operator must reconfigure downstream distribution lines to ensure that product is applied in the proper location on the tilling implement. One possible solution is disclosed in U.S. Pat. No. 5,855,303.